Road train lighting

[mavrick0]

If you look up the part number for the optocoupler you ordered you'll be able to find a data sheet which will give you a schematic and pin layout.

As for the Bluetooth still functioning as I said it's as simple as putting a micro switch in the plate for the king pin. You need to do the same with the sstronix unless you want it sitting there with all it's clearance lights on with no tractor hooked up.